Title: NixOS Bento: new reporting feature
       Author: Solène
       Date: 05 September 2022
       Tags: bento nixos nix
       Description: 
       
       # Bento
       
       Bento received a new feature, it is now able to report if the remote
       hosts are up-to-date, how much time passed since their last update, and
       if they are not up-to-date, how long passed since the configuration
       change.
       
 (HTM) Bento git project repository
       
       As Bento is using SFTP, it's possible to deposit information on the
       central server, I'm currently using log files from the builds, and
       compare this date to the date of the configuration.
       
       This will be very useful to track deployments across the fleet.  I plan
       to also check the version expected for a host and make them report
       their version after an update, this should possible for flakes system
       at least.
       
 (HTM) Asciinema demonstration (was done during development, doesn't contain report features)
       
       # Demonstration
       
       I pushed a new version affecting all hosts on the SFTP server, and run
       the status report regularly.
       
       This is the output 15 seconds after making the changes available.
       ```text
       status of kikimora  not up to date 🚩 (last_update 15m 6s ago) (since config change 15s ago)
       status of      nas  not up to date 🚩 (last_update 12m  ago) (since config change 15s ago)
       status of     t470  not up to date 🚩 (last_update 16m 9s ago) (since config change 15s ago)
       status of       x1  not up to date 🚩 (last_update 16m 24s ago) (since config change 14s ago)
       ```
       
       This is the output after two systems picked up the changes and reported
       a success.
       ```
       status of kikimora  not up to date 🚩 (last_rebuild 16m 46s ago) (since config change 1m 55s ago)
       status of      nas      up to date 💚 (last_rebuild 8s ago)
       status of     t470  not up to date 🚩 (last_rebuild 17m 49s ago) (since config change 1m 55s ago)
       status of       x1      up to date 💚 (last_rebuild 4s ago)
       ```
       
       This is the output after all systems reported a success.
       ```
       status of kikimora  up to date 💚 (last_rebuild 0s ago)
       status of      nas  up to date 💚 (last_rebuild 1m 24s ago)
       status of     t470  up to date 💚 (last_rebuild 1m 2s ago)
       status of       x1  up to date 💚 (last_rebuild 1m 20s ago)
       ```